One goal driving the wireless communication industry is providing consumers with increased bandwidth. The use of carrier aggregation in current generation communications provides one possible solution for achieving this goal. Carrier aggregation enables a wireless carrier to increase bandwidth by simultaneously using multiple frequencies for a single communication stream. While an increased amount of data is provided to the end user, carrier aggregation implementation is complicated by noise created at the harmonic frequencies due to the frequencies used for data transmission. For example, 700 MHz transmissions may create harmonics at 2.1 GHz, which interfere with data broadcast at 2 GHz frequencies.
The design complexity of mobile radio frequency (RF) chips (e.g., mobile RF transceivers) is complicated by added circuit functions for supporting communication enhancements, such as carrier aggregation. Designing mobile RF transceivers may include using acoustic filters and resonators for processing signals carried in a carrier aggregation system. Many passive devices may be included in such filters and resonators. Each of these passive devices may include many inductors and capacitors.
Existing die scale surface acoustic wave (SAW) packaging (DSSP2) includes 2D inductors on a capping wafer. These 2D inductors generate a vertical magnetic field on the SAW filter, which interferes with the filter's functionality. There is also not enough space to include many inductors for generating a phase shifter for duplexers or other multiplexers. Additionally, existing process flows for DSSP2 devices are complex for fabricating both 2D inductors and through substrate vias (TSVs) for interconnects.
Fabricating high performance filters and resonators in an efficient and cost-effective manner for supporting communication enhancements is problematic. Increasing the quality (Q) of the inductors used by the filters and resonators is also an issue. Reducing the electromagnetic coupling and interference between the inductors in a device, while also increasing a number of inductors in the device, would be beneficial.